/*******************************************************************************
 * @file cyclic_list.h
 * @brief:
 *
 *
 * Author: Kevinx
 *
 * Copyright (c) 2015 Kevinx. All Rights Reserved.
 *
 * CONFIDENTIALITY AND LIMITED USE
 *
 * This software, including any software of third parties embodied herein,
 * contains information and concepts which are confidential to Kevinx
 * and such third parties. This software is licensed for use
 * solely in accordance with the terms and conditions of the applicable
 * license agreement with Kevinx or its authorized distributor.
 ************************************************************************************/
#ifndef __CYCLIC_LIST_H__
#define __CYCLIC_LIST_H__

#define likely(x) __builtin_expect(!!(x), 1)
#define unlikely(x) __builtin_expect(!!(x), 0)

#ifndef NULL
#define NULL (0)
#endif

struct list_head
{
    struct list_head* next;
    struct list_head* prev;
};

#define LIST_HEAD_INIT(name) { &(name), &(name) }

static inline void INIT_LIST_HEAD(struct list_head *head)
{
    head->next = head;
    head->prev = head;
}

/*
 * Insert a new entry between two known consecutive entries.
 *
 * This is only for internal list manipulation where we know
 * the prev/next entries already!
 */
static inline void __list_add(struct list_head *node,
                              struct list_head *prev,
                              struct list_head *next)
{
    next->prev = node;
    node->next = next;
    node->prev = prev;
    prev->next = node;
}

/**
 * list_add - add a new entry
 * @new: new entry to be added
 * @head: list head to add it after
 *
 * Insert a new entry after the specified head.
 * This is good for implementing stacks.
 */
static inline void list_add(struct list_head *node, struct list_head *head)
{
    __list_add(node, head, head->next);
}

/**
 * list_add_tail - add a new entry
 * @new: new entry to be added
 * @head: list head to add it before
 *
 * Insert a new entry before the specified head.
 * This is useful for implementing queues.
 */
static inline void list_add_tail(struct list_head *node, struct list_head *head)
{
    __list_add(node, head->prev, head);
}

/*
 * Delete a list entry by making the prev/next entries
 * point to each other.
 *
 * This is only for internal list manipulation where we know
 * the prev/next entries already!
 */
static inline void __list_del(struct list_head *prev, struct list_head *next)
{
	next->prev = prev;
	prev->next = next;
}

/**
 * list_del - deletes entry from list.
 * @entry: the element to delete from the list.
 * Note: list_empty() on entry does not return true after this, the entry is
 * in an undefined state.
 */
static inline void list_del(struct list_head *entry)
{
	__list_del(entry->prev, entry->next);
	entry->next = NULL;
	entry->prev = NULL;
}

/**
 * list_empty - tests whether a list is empty
 * @head: the list to test.
 */
static inline int list_empty(const struct list_head *head)
{
	return head->next == head;
}

/**
 * list_is_singular - tests whether a list has just one entry.
 * @head: the list to test.
 */
static inline int list_is_singular(const struct list_head *head)
{
	return !list_empty(head) && (head->next == head->prev);
}

#ifndef offsetof
#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
#endif 

#define container_of(ptr, type, member) ({			\
	const typeof( ((type *)0)->member ) *__mptr = (ptr);	\
	(type *)( (char *)__mptr - offsetof(type,member) );})

/**
 * list_entry - get the struct for this entry
 * @ptr:	the &struct list_head pointer.
 * @type:	the type of the struct this is embedded in.
 * @member:	the name of the list_struct within the struct.
 */
#define list_entry(ptr, type, member) \
	container_of(ptr, type, member)

/**
 * list_entry - get the struct for this entry
 * @ptr:	the &struct list_head pointer.
 * @type:	the type of the struct this is embedded in.
 * @member:	the name of the list_struct within the struct.
 */
#define list_for_each_entry(pos, head, member)				\
	for (pos = list_entry((head)->next, typeof(*pos), member);	\
	     &pos->member != (head); 	\
	     pos = list_entry(pos->member.next, typeof(*pos), member))

/**
 * list_entry - get the struct for this entry
 * @ptr:	the &struct list_head pointer.
 * @type:	the type of the struct this is embedded in.
 * @member:	the name of the list_struct within the struct.
 */
#define list_for_each(pos, head) \
	for (pos = (head)->next; pos != NULL; pos = pos->next)

#endif /* __CYCLIC_LIST_H__ */
